OverlayManager refactor and Flash (#1218)

* Flash component, overlay and shader
Add BeginDraw method to Overlay.cs

* Add flash icons, sounds

* Progress

* Multiple overlays without enums

* This is probably the worst way to do this IDK

* Remove nullable reference type

* Add AttackEventArgs as parameter to OnHitEntities
MeleeWeaponComponent.Attack now continues when OnHitEntities returns true (it hit something)
Add OverlayType enum so client and server can agree on overlay ids
Move IConfigurable to its own file
Add AoE flash with shorter duration
Flashing someone slows them down

* Add arc to flash
Set item size to something reasonable
Remove chat log message when flash burns out

* Remove unused interface

Content.Shared/GameObjects/Components/Mobs/SharedOverlayEffectsComponent.cs

@@ -1,6 +1,14 @@
 using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using JetBrains.Annotations;
 using Robust.Shared.GameObjects;
+using Robust.Shared.Prototypes;
 using Robust.Shared.Serialization;
+using Robust.Shared.Timers;
+using Robust.Shared.ViewVariables;
+using YamlDotNet.RepresentationModel;
+using Component = Robust.Shared.GameObjects.Component;
 
 namespace Content.Shared.GameObjects.Components.Mobs
 {
@@ -13,21 +21,72 @@ namespace Content.Shared.GameObjects.Components.Mobs
         public sealed override uint? NetID => ContentNetIDs.OVERLAYEFFECTS;
     }
 
-    public enum ScreenEffects
+    [Serializable, NetSerializable]
+    public class OverlayContainer
     {
-        None,
-        CircleMask,
-        GradientCircleMask,
+        [ViewVariables(VVAccess.ReadOnly)]
+        public string ID { get; }
+
+        public OverlayContainer([NotNull] string id)
+        {
+            ID = id;
+        }
+
+        public OverlayContainer(OverlayType type) : this(type.ToString())
+        {
+
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (obj is OverlayContainer container)
+            {
+                return container.ID == ID;
+            }
+
+            if (obj is string idString)
+            {
+                return idString == ID;
+            }
+
+            return base.Equals(obj);
+        }
+
+        public override int GetHashCode()
+        {
+            return (ID != null ? ID.GetHashCode() : 0);
+        }
     }
 
     [Serializable, NetSerializable]
     public class OverlayEffectComponentState : ComponentState
     {
-        public ScreenEffects ScreenEffect;
+        public List<OverlayContainer> Overlays;
 
-        public OverlayEffectComponentState(ScreenEffects screenEffect) : base(ContentNetIDs.OVERLAYEFFECTS)
+        public OverlayEffectComponentState(List<OverlayContainer> overlays) : base(ContentNetIDs.OVERLAYEFFECTS)
         {
-            ScreenEffect = screenEffect;
+            Overlays = overlays;
         }
     }
+
+    [Serializable, NetSerializable]
+    public class TimedOverlayContainer : OverlayContainer
+    {
+        [ViewVariables(VVAccess.ReadOnly)]
+        public int Length { get; }
+
+        public TimedOverlayContainer(string id, int length) : base(id)
+        {
+            Length = length;
+        }
+
+        public void StartTimer(Action finished) => Timer.Spawn(Length, finished);
+    }
+
+    public enum OverlayType
+    {
+        GradientCircleMaskOverlay,
+        CircleMaskOverlay,
+        FlashOverlay
+    }
 }